It is well known that organic materials such as a resin and the like degrade by a function of ultraviolet light of solar light. In the resin, coloration or decrease in strength occurs by the ultraviolet light, and in a variety of functional organic materials, decomposition is caused by the ultraviolet light and their functions degrade.
In order to prevent the degradation of these organic materials caused by the ultraviolet light, an ultraviolet light absorber is generally used. For example, in a display device, it is generally practiced to add the ultraviolet light absorber to optical films such as polarizer protective films and the like thereby preventing the coloration of these optical films. Also, in order to prevent the degradation of a near-infrared light absorber included in anti-reflection films caused by the ultraviolet light, the ultraviolet light absorber is added to the anti-reflection films. Further, a variety of organic materials such as fluorescent elements, phosphorescent elements, and the like are used in a luminous element of organic EL displays. That is to say, in order to prevent the degradation of the organic materials caused by the ultraviolet light, the ultraviolet absorber is added to a surface film of the display.
In human bodies, it is well known that skins and eyeballs get tanned by the ultraviolet light, causing various maladies. The bad effect to the eyeballs caused by the ultraviolet light includes, for example, a possible development of a cornea inflammation when the eyes are exposed to solar light in such an outdoor place where there are lots of ultraviolet light. As for the bad effect to lens, a cataract might be developed by the accumulated ultraviolet light.
In order to prevent various diseases related to eyeballs caused by the ultraviolet light, it is generally practiced to add the ultraviolet absorber to glass lens or contact lens, thereby preventing the ultraviolet light from reaching the eyes.
In each of the above mentioned uses, it is required to fully block the ultraviolet light. In other words, it is required to fully block the solar light of 400 nm or less. It is known that conventionally used ultraviolet light absorbers have weakness in that they do not fully absorb a long wavelength range of 350 to 400 nm, in particular, 380 to 400 nm, and therefore, many ultraviolet light absorbers have been proposed that could efficiently absorb the ultraviolet light in these long wavelength ranges. For example, as described in patent documents 1 to 3, benzooxadinone derivatives, triazine derivatives, benzotriazole derivatives, and the like, have been proposed in each of the above mentioned uses. However, benzooxadinone derivatives described in patent document 1 have generally low light resistance, and therefore, it is anticipated that the ultraviolet light absorbing property degrades with a long team use. In addition, triazine derivatives and benzotriazole derivatives described in patent documents 2 and 3 have low long wavelength range absorption property, and therefore, the ultraviolet absorbing function is not sufficient.
Patent documents 4 to 5 describe that, by modifying benzotriazole with sesamol, the light of the long wavelength range can be efficiently absorbed. However, it is difficult to apply it for each of the above mentioned uses, since the absorption of visible light range of 400 to 420 nm is strong, and therefore, the optical film or glass lens turns yellow when the above mentioned compound is added to them.